Machine for grinding threads



Nov. 24, 1942. F. TU RRETTINI 2,303,008

" 4 MACHINE FOR GRINDING THREADS Filed March 28, 1941 (6 h ///A Z/ 8/1'o 1'1 1 N 15 ,ZTa mm% f Turre Y a i 1% Patented Nov. 24, 1942 UNTEDSTATES PATENT OFFICE MACHINE FOR i nfi TfiREADS I Application March 28,1941, Serial No. 385,761 In Switzerland May 15, 1940 Claims.

The present invention relates to a thread grinding machine having atruing device for the grinding wheel, which device is mounted on thetable carrying the work piece.

It is an object of the invention to provide a machine of the above kindhaving a truing device which operates in a position which is in exactrelation to the grinding wheel in order that the profile of the lattermay be engendered always in the same position.

Another object of the invention is to provide means which permit ofbringing the truing device instantaneously into the exact workingposition.

The machine according to the invention is characterized by two stopscarried by the machine frame and cooperating one with an abutmentcarried by the table and the other with an abutment carried by the nutof the guide screw, which nut is mounted on the table insuch a mannerthat it can slide in the'latter without turning with the screw, themachine comprises also a device exerting a horizontal traction upon thetable, and a hand control lever which permits of changing the directionof said traction so as to apply either the abutment of the nut againstthe corresponding stop on the frame, position in which the work piececan be ground, or the abutment of the table against the correspondingstop on the frame, position in which the grinding wheel can be trued.

The annexed drawing represents, by way of example, one embodiment of thepresent inven-- tion.

Fig. 1 is a transverse section. The Figures 2 and 3 show two differentviews of a detail.

In the figures, I designates the grinding wheel carried by a specialsupport la, and 9 is the table of the machine, adapted to slide on theframe ii! of said machine. Said table which is intended to carry thework piece, the thread of which is to be rectified, presents for thispurpose a spindle 2, capable of turning in the head stock 29., and aback centre 3 between which is disposed said piece to which the spindle2 imparts a rotatory movement. 4 is the truing device of the grindingwheel I placed in advance of the table 9. 5 is the driving pinion of thespindle, 6 is the head carrying the reduction gears the composition ofwhich determines the pitch of the thread to be rectified, I is thedriving pinion of the guide screw H] which is maintained rotatablywithout axial play in a bearing 8 integral with the table 9.

The guide screw ID has its threaded part II engaged in a tubular nut l2which is axially movable in a bore I4 of the table. To thisnut I2 isfixed radially a finger 15 which can slide along in a slot of a bar [5fixed to the table 9,

this finger prevents the nut from turning, while leaving to it thepossibility to slide longitudinally.

The nut l2 terminates in an abutment H which during grinding bears upona, fixed stop 13 mounted on the frame l9.

The table 9 carries a second abutment 29 which when the truing apparatus4 istobe brought to the working position in front of the grinding wheelI, has to bear upon a stop 2| also mounted on the frame I9.

This will be obtained by operating by means of a pinion 23 a rack 22guided in the tablefl; this pinion carried by'the table is integral withan axis 24 upon which is disposed a control lever 25 which is providedwith a stop button 29 adapted to render the same immovable on the tablein two distinct-fixed positions 30 and 3| (see Figs. 2 and 3). r r

The chain 32 of the counter-weight 33 is fastened at 26 on the rack 22;it passes between two return pulleys 21 and 28 and is rolled up in parton one or the other of said pulleys according to the relative positionof the fastening point 26 with respect to the table 9.

Fromthe above it is seen that the nut l2 has no rigidand permanentconnection with the frame l9 and that it can be removed rapidly from thestop l8'when one wishes to pass from the grinding position to the truingposition.

This is obtained by provoking by means of lever 25 passing from theposition 30 to the position 3|, and pinion 23 a sliding of the rack 22carrying the fastening point 25 of the chain of the counter-weight 33which exerts upon the table 9 a traction assuring contact between theabutment H and the stop I8 so long as the chain passes over the pulley21.

When by the action of the lever 25 the movement of the fastening point26 causes the chain 32 to pass from the pulley 21 to the pulley 28, thetraction exerted upon the table by the counter-weight will be in theinverse direction and will move the table so as to bring the abutment 20into contact with the stop 2|. This contact will be maintained by theimmobilization at 3| of the arm 25.

It is seen that in this machine the rapid action of a hand control leverenables to pass the table alternately from the position of grinding thework piece to the position for truing the grinding wheel; the constancyof the two positions, through the action of abutments, ensures greatprecision.

From the foregoing, it is believed that the construction and advantagesof the present invention may be readily understood by those skilled inthe art without further description, it being borne in mind thatnumerous changes may be made in the details disclosed without departingfrom the spirit of the invention as set out in the following claims.

What is claimed and desired to be secured by Letters Patent is:

1. A machine for grinding threads including a frame, a table carrying awork piece and movable relative to the frame, a grinding wheel adjacentthe table for operating on the work piece, a truing device for thegrinding wheel mounted on the table, a guide screw having a threadedouter end and J'ournaled in the table on the under side thereof, a nutthreaded on the guide screw and mounted for sliding but non rationalmovement relative to the table, an abutment on the outer end of the nut,an abutment on the under side of the table in alignment with theabutment on the nut, two additional oppositely facing abutments mountedon the frame betweenthe first mentioned abutments and in alignmenttherewith, and means for exerting a horizontal traction on the table inopposite directions so as to apply either the abutment on the nutagainst the corresponding abutment on the frame in which position thework piece can be ground or the abutment on the table against thecorresponding abutment in which position the grinding wheel can betrued.

2. A machine for grinding threads as claimed in claim 1 in which themeans for exerting the horizontal traction on the table are handoperated means and locking means are provided for locking the table ineither position.

3. A machine for grinding threads as claimed Q in claim 1 in which thetraction exerting means includes a counterweight, a flexible memberhaving one end fixed to the counterweight, two adjacent pulleys betweenwhich passes the flexible member prior to its being rolled upon one orthe other of said pulleys according to the direction of traction exertedupon the table and hand operated means including a rack adapted to slidein the table and to which is pivotally mounted the other end of theflexible member, a pinion carried by the table and engaging said rack,an

operating organ carried by the table and controlling the pinion, saidorgan being capable of assuming two fixed positions whereby the positionof the pivot point of the rack and flexible member with respect to thepulleys is changed when the organ passes from one of its positions tothe other.

4. In a machine for grinding threads comprising a frame, a work tablemounted slidingly on said frame, and a grinding wheel truing devicemounted on said table outside of the stocks, in combination. a guidescrew mounted in the table with its driving gear, a nut engaging saidscrew and mounted slidingly in the table, said nut being provided withan axial tubular extension carrying an end abutment, a two ended stopmounted on the frame and cooperating by one end with said nut abutmentand by the other end with a fixed abutment of the table, and a handcontrolled horizontal traction device for quick table displacementwithin the limits of said abutments, from the thread grinding positionto the wheel truing position and vice versa.

5. In a machine for grinding threads comprising a frame, a Work tablemounted slidingly on said frame, and a grinding wheel truing devicemounted on said table outside of the stocks, in combination, a guidescrew mounted in the table with its driving gear, a nut engaging saidscrew and mounted slidingly in the table, said nut being provided withan axial tubular extension carrying an end abutment, a two ended stopmounted on the frame and cooperating by one end with said nut abutmentand by the other end with a fixed abutment of the table, and a handcontrolled horizontal traction device for quick table displacementwithin the limits of said abutments, from the thread grinding positionto the wheel truing position and vice-versa, said horizontal tractiondevice comprising a handle mounted on the table apron, a pinion fixed onthe axis of said handle, a locking device carried by this handle andcooperating with two diametrally opposed locking positions, a rackmounted slidingly in the table and engaging said pinion, a. flexibleelement, fastened by one end in a point of said rack, two adjacentpulleys mounted in the machine frame and a counterweight hung by theother end of said flexible element led down between said pulleys.

' FERNAND TURRET'IINI.

